1. Field of the Invention
This invention is directed to a magnetic bubble domain relational data base system, and in particular to such a system having bubble domain storage which can be selectively accessed in a number of ways to implement various operations required in a relational data base system.
2. Description of the Prior Art
The use of data in a relational data base system is described in an article by E. F. Codd, beginning at page 377 of the June 1970 Communications of the ACM, Volume 13, No. 6. In contrast with conventional data base systems which generally use some form of hierarchical structure where the storage and retrieval of items of information are dependent upon a previously determined key reference which has to be used for accessing data and for writing data back into the memory, a relational data base system does not organize data in a rigid fashion. Many different sets, or relations, of data may be stored in an array where accessing of any of the sets of data may be accomplished by simply naming the relation and those domains of the relation that are desired.
Relational data base systems are an attempt to simplify the user's view of information in the entire data base. In this system, a relation is viewed as a table of columns and rows. For example, a table entitled "Parts List" may contain columns headed "Part Number", "Part Name", "Color", "Weight". The "relation" is the table entitled "Parts List", while the various column headings are the attributes within the table itself. Another table may include as a column therein one of the columns in the first table. Thus, the attribute "Part Number" may be a portion of another table.
From the user's point of view the data base is a collection of relations, or tables. A user can use common attributes to obtain additional relations. That is, the user can look to a common attribute (such as "Part Number") which appears in two tables and then construct another table comprised of columns from the first and second tables. In this way, a new relationship can be established which is a new table having columns which previously were not combined in any single table. In this manner, the number of relations is increased.
Other articles dealing generally with relational data bases include the following:
1. C. S. Lin et al, ACM Transactions on Data Base Systems, Volume 1, No. 1, March 1976, pp. 53-65. PA1 2. E. A. Ozkarahan et al, National Computer Conference, 1975, pp. 379-387. PA1 3. Computer Systems Research Group, University of Toronto, Toronto, Canada, Report M5S1A4 (to appear as No. 30 of ENGINEERING FORUM, a publication of the faculty of Applied Science and Engineering of the University of Toronto, Toronto, Ontario, Canada).
The present invention seeks to utilize magnetic bubble domain storage as a key component in a data base management system. More particularly, the present invention is directed to apparatus for using relational data bases with bubble domain storage, where the natural attributes of two-dimensional bubble storage can be utilized advantageously. In order to do so, two types of known bubble domain storage, a major/minor loop storage and the bubble lattice storage, are utilized as illustrative examples. Bubble domain major/minor loop storage is described in U.S. Pat. No. 3,618,054 and also in U.S. Pat. No. 3,879,585. The bubble lattice storage is described in copending application Ser. No. 632,604 filed Nov. 14, 1975 (now U.S. Pat. No. 4,052,710) which is a continuation of Ser. No. 395,336 filed Sept. 7, 1973 and assigned to the common assignee. In addition, this type of bubble domain storage has been described by B. A. Calhoun and others at the 20th Annual Conference on Magnetism and Magnetic Materials, Dec. 3-6, 1974, San Francisco, Calif., (papers 7D-1, 7D-2, 7D-3, 7D- 4).
Prior art relating to magnetic bubble domain systems has been largely directed to conventional types of storage systems where data is stored and retrieved by fixed addresses. An attempt to utilize bubble domains for data management is described in copending application Ser. No. 556,378, filed Mar. 7, 1975 (now U.S. Pat. No. 4,040,018) in the name of H. Chang et al, and assigned to the present assignee. In that application, data management can be provided by a plurality of shift registers which are linked by binary switches. These switches enable two streams of data to either cross one another non-destructively or to bypass one another. In this manner, a variety of data structures can be provided, such as last in - first out, and first in - first out, as well as dynamic rearrangement of data items.
Accordingly, it is a primary object of the present invention to provide a magnetic bubble domain relational data base system.
It is another object of this invention to provide a system utilizing the natural features of magnetic bubble domain storage for performance of data operations using relational data base algebra.
It is another object of the present invention to utilize two forms of magnetic bubble domain storage in a system in which data is stored and accessed in terms of its relation to other data.